You can (or could) buy small assortments of JIS fasteners for about $10 at O'Reillys, as of a couple years ago. They were in a plastic organizer about 7"x10" and included various sizes.
This would be expensive if you had many to replace, but maybe for high visibility places you could use these shiny fasteners.
Steve H. - KE0KNH
Colo Springs, CO
'78 FJ40, '89 FJ62, '98 4Runner